A television broadcast station may broadcast a primary video feed from multiple sources, such as live events, studio broadcasts, or pre-recorded shows, and may process multiple video feeds such that the broadcast appears to overlay multiple feeds as a “picture-in-picture,” or “video-in-video” feed.
Digital video processing of video transmissions increases transmission latency, which may affect the synchronization of a video feed with a corresponding audio feed. To achieve adequate bit rates, videos before transmission are typically compressed, that is, encoded, to reduce bandwidth requirements.
MPEG-1, MPEG-2, and H.264 are common compression standards, the first two having been widely replaced by the more recent H.264 standard. The H.264 standard is a publication of the International Telecommunication Union—Telecommunication Standardization Sector (ITU-T), also referred to as the MPEG-4 Part 10, Advanced Video Coding (AVC) standard 14496-10 of ISO/IEC, the teachings of which are incorporated herein by reference. H.264/AVC has a reference software implementation that includes a Joint Model (JM) Reference H.264 Encoder and a JM Reference H.264 Decoder. The reference software is accompanied by the H.264/AVC Reference Software Manual, authored by the Joint Video Team (JVT) of ISO/IEC MPEG & ITU-T VCEG (working groups: ISO/IEC JTC1/SC29/WG11 and ITU-T SG16 Q.6), the teachings of which are also incorporated herein by reference.
A basic H.264 compression profile, the constrained baseline profile, includes features that are compliant with most H.264 profiles in common use.
An H.264 encoder compresses a video by frames, that is, by individual images or pictures. Each frame is compressed by determining a residual difference between content of each macroblock of pixels in the frame and a prediction of that macroblock content. For inter-frame prediction, also referred to as motion-compensated prediction, predictions are based on macroblocks of prior frames. For intra-frame prediction, prediction is based on macroblocks from the same frame. High Efficiency Video Coding (HEVC) also referred to as H.265, is a newer standard being developed that includes similar compression methodology.
Video feeds compressed by the H.264 standard may contain multiple distinct videos. U.S. Pat. No. 8,369,397 to Bordes et al., whose disclosure is incorporated herein by reference, describes the insertion of a logo over a main video feed by several mechanisms, such as including the logo as a redundant coded picture or by means of flexible macroblock ordering (FMO). U.S. Pat. No. 6,931,660 to Kalluri et al., whose disclosure is incorporated herein by reference, describes merging two MPEG 2 videos.